Baghdad, Aug. 19 (Reuters): One man was carried away on a stretcher with a long metal rod stuck in his face. Another walked away from the destruction completely covered in blood as he held his briefcase.

But others were not so lucky when a suspected suicide truck bomb ripped through the UN headquarters in Baghdad, killing at least 13 and wounding dozens of others.

American soldiers, stripped down to T-shirts, combed through the rubble for victims still trapped inside as black smoke drifted skywards and helicopters hovered overhead.

Hundreds of people were winding up the day’s work when the bomb shook the building. “We were inside and suddenly there was a huge explosion. The whole building shook,” said Fouad Victor, a UN worker. The UN uses the Canal Hotel in eastern Baghdad as the headquarters for a wide number of its agencies, employing hundreds of staff.

It was the base for weapons inspectors during the hunt for Saddam’s alleged weapons of mass destruction. After the war that toppled Saddam in April, the UN headquarters focused mostly on humanitarian aid for Iraq. But today it was caught up in the violence rattling Iraq every day.

Hysterical Iraqis tried to get past US soldiers to find the fate of relatives trapped inside the building, which was turned into twisted metal and flattened ceilings and walls.

One UN employee had gone across town to another office and returned to find ambulances speeding by and American soldiers scrambling through the destruction.

She sat on the street and wept as she told a soldier that her niece was inside. “Let me in please. Let me in,” she said, waving her UN badge. “Oh God, why is this happening to us' Oh God, let me in.”

When the truck smashed into the building, a news conference was being held inside on mines and unexploded ordnance. Grant Hodgson, a journalist attending the conference, said the lights went out after a sudden huge blast. Smoke filled the rooms and nobody could see as they tried to run away. Outside at the scene of the blast he saw severed limbs scattered across a wide area and a three-foot deep crater. “I saw legs and arms, charred remains... there were at least three dead right there,” he said moments afterwards.

US helicopters flew medical evacuations in rotation, three landing and taking off at a time, ferrying the dead and wounded to a nearby military field clinic. One man, a gatekeeper at the UN building, said he was standing nearby when the blast occurred. His face drained and his hands covered in blood after trying to help the wounded, he said he had done everything he could but it wasn’t enough.